EP3338934A1 - Method for producing a drill shaft for a wet trepanning drill bit - Google Patents

Abstract

Method for producing a drill shaft (18, 48) for a wet drill bit (10, 40), which produces a drill hole (27) with a drill hole diameter (d 2 ) and a drill core (26) with a core diameter (d 1 ), in which N , N ‰¥ 1 strip materials (31; 53A, 53B, 53C) are formed into a tubular body (32, 54) and the tubular body (32, 54) is materially connected at the strip edges via N connecting welds (31; 53A, 53B, 53C). at least one strip material of the N, N ‰¥ 1 strip materials (31; 53A, 53B, 53C) is provided with at least one indentation (37A, 37B, 37C) before the material-locking connection of the strip edges.

Description

Technical area

The present invention relates to a method for producing a drill stem for a wet drill bit according to the preamble of claim 1.

State of the art

Drill bits consist of several drill bit sections, which are designed as a cutting section and Bohrschaftabschnitt. The cutting portion includes a ring portion and one or more cutting segments that are welded, brazed, bolted, or attached to the ring portion in another suitable manner of attachment to the ring portion. The drill shank portion includes a tubular drill shank, a lid, and a spigot end over which the drill bit is secured in the tool receptacle of a core drill. The drill stem is made of a tubular material or of a flat strip material, which is formed into a tube and connected to the strip edges by longitudinal seam welding. The cutting section and drill shaft section are detachably or non-detachably connected by means of a connecting device. In drill bits with a permanent connection between the cutting section and the drill shaft section, the annular section of the cutting section and the drill shaft may be monolithic, alternatively, the annular section may be materially connected to the drill shaft.

In drilling operation, a drill bit in a workpiece produces a core diameter drill core and a bore diameter hole. The cutting segments form a cutting ring having an inner diameter corresponding to the core diameter and an outer diameter corresponding to the borehole diameter. When drilling a distinction between wet drilling and dry drilling. Drill bits for wet drilling (wet drill bits) differ in the construction of drill bits for dry drilling (dry drill bits). When wet drilling a cooling and rinsing liquid is required, which cools the cutting segments of the drill bit as coolant and removed as drilling fluid cuttings from the wellbore. Clean cooling and rinsing fluid is usually supplied through an internal gap between the drill core and the drill stem and with cuttings staggered, spent cooling and rinsing liquid discharged through an outer gap between the drill stem and the wellbore.

In order to transport sufficient cooling and rinsing fluid to the machining location in the workpiece, the rule applies to the construction of wet drill bits that the inner gap should have a width of at least 0.4 mm taking into account all permissible deviations, whereby the width of the inner gap is also referred to as inner overhang , When wet drilling reinforced concrete, i. of concrete with embedded reinforcing bars, iron wedges may form during drilling, separated from the reinforcing bar by the wet bit and separating from the core. The iron wedges may become wedged in the inner gap between the drill shank and the drill core and lead to an interruption of the drilling process and a standstill of the core drill. In order to reduce the risk of jamming iron wedges in the inner gap between the core and the drill shank, the inner overhang should be limited to values smaller than 0.4 mm, in particular smaller than 0.2 mm. The smaller the inner gap between the core and the inside of the drill shank, the lower the risk that a severed iron wedge of a reinforcing iron will come loose from the core and penetrate into the inner gap between the core and the inside of the drill shank.

In order to transport sufficient cooling and rinsing liquid to the machining point in the workpiece in the case of wet drill bits with a small internal projection, the wet drill bits should be provided with transport channels for the cooling and rinsing liquid. The disadvantage is that the production of transport channels for the cooling and rinsing liquid on the inside of the drill shank produces a high production cost.

Presentation of the invention

The object of the present invention is to provide a method for producing a drill stem for a wet drill bit with which transport channels for a cooling and rinsing liquid can be generated on an inner side of the drill shaft. The manufacturing effort in the production of the drill shank should be as low as possible.

This object is achieved according to the invention in the method mentioned by the features of independent claim 1. Advantageous developments are specified in the dependent claims.

The method for producing a drill shank for a wet drill bit according to the invention is characterized in that at least one strip material of N, N ≥ 1 strip materials is provided with at least one recess before the material-locking connection of the strip edges. The drill shank is made of a strip material (N = 1) or several strip materials (N ≥ 2), wherein the number of strip materials used corresponds to the number of joint welds. In the manufacture of the drill shank, the strip materials are formed into a tube body and welded to the abutting strip edges. The production of the drill shank by shaping and welding strip materials makes it possible to produce indentations on the inside of the drill shank with little manufacturing effort, which serve as transport channels for the cooling and rinsing liquid in the finished drill shank. The recesses may be created on an inside of the drill shank, on an outside of the drill shank, or on an outside and inside of the drill shank.

In a first preferred variant, the N, N ≥ 1 strip materials are formed into a spiral tube body and the spiral tube body is bonded to the band edges via N spiral connection weld seams. A drill stem, which is formed as a welded spiral tube body, has at least one spiral connection weld seam, which acts as a stiffening element for the drill stem and increases the rigidity of the drill stem relative to a tubular drill stem of the same wall thickness. Alternatively, band materials with lower wall thicknesses can be used which have the same rigidity in the finished drill stem as a tubular drill stem. Thus, the use of a welded spiral tube body as a drilling shank either increases the rigidity of the drill shank in drilling operation and / or reduces the weight of the drill shank. A drill stem with a higher rigidity improves the stability of the drill shank during drilling.

In a second preferred variant, the N, N ≥ 1 strip materials are formed into a longitudinal tube body and the longitudinal tube body is bonded to the band edges over N longitudinal connecting weld seams. A drill stem, which is designed as a welded longitudinal tube body, has at least one longitudinal connecting weld, which acts as a stiffening element for the drill stem and increases the rigidity of the drill stem relative to a tubular drill stem of the same wall thickness. Alternatively, band materials with lower wall thicknesses can be used which have the same rigidity in the finished drill stem as a tubular drill stem. Thus, the use of a welded longitudinal tube body as a drilling shank either increases the rigidity of the drill shank in drilling operation and / or reduces the weight of the drill shank. A drill stem with a higher rigidity improves the stability of the drill shank during drilling.

In a first preferred variant, the at least one recess of the tubular body is produced on an inner side of the drill shaft. In the production of the drill shank are formed the strip materials to the tubular body and welded to the strip edges. Before the strip edges are welded, recesses are produced on the inside of the tubular body, which serve as transport channels for clean cooling and rinsing liquid in the drilling operation. The number of wells and the geometry of the wells can be adapted to the required amount of liquid of the clean cooling and rinsing liquid.

In a second preferred variant, the at least one recess of the tubular body is produced on an outer side of the drill shaft. During production of the drill shank, the strip materials are formed into the tube body and welded to the strip edges. Before the strip edges are welded, recesses are produced on the outside of the tubular body, which serve as transport channels for cuttings with spent, used cooling and rinsing liquid in the drilling operation.

In a third preferred variant, at least one depression of the tubular body is produced on an inner side of the drill shank and at least one depression of the tubular body is produced on an outer side of the drill shank. During production of the drill shank, the strip materials are formed into the tube body and welded to the strip edges. Before the strip edges are welded, recesses are produced on the inside and outside of the tube body. The indentations on the inside of the drill shank serve as transport channels for clean cooling and rinsing fluid, and the indentations on the outside of the drill shank serve as transport channels for spent cooling and rinsing fluid mixed with drill cuttings.

embodiments

Embodiments of the invention are described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematic and / or slightly distorted form. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below or limited to an article that would be limited in comparison with the subject matter claimed in the claims. For given design ranges, values lying within the specified limits should also be disclosed as limit values and be arbitrarily usable and claimable. For simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar function.

FIG. 1

eine erste Ausführungsform einer Nassbohrkrone mit einem spiralrohrförmigen Bohrschaft, der mittels des erfindungsgemäßen Verfahrens zur Herstellung eines Bohrschaftes mit Vertiefungen auf der Innenseite hergestellt wurde;

FIGN. 2A, B

einen Längsschnitt durch den Bohrschaft der ersten Nassbohrkrone der FIG. 1 entlang der Schnittlinie A-A in FIG. 1B (FIG. 2A) sowie ein Detail des Bohrschaftes der FIG. 2A in einer vergrößerten Darstellung (FIG. 2B);

FIG. 3

eine zweite Ausführungsform einer Nassbohrkrone mit einem längsnahtgeschweißten Bohrschaft, der mittels des erfindungsgemäßen Verfahrens zur Herstellung eines Bohrschaftes mit Vertiefungen auf der Außen- und Innenseite hergestellt wurde;

FIGN. 4A, B

einen Querschnitt durch den Bohrschaft der zweiten Nassbohrkrone der FIG. 3 entlang der Schnittlinie A-A in FIG. 3 (FIG. 4A) sowie ein Detail des Bohrschaftes der FIG. 4A in einer vergrößerten Darstellung (FIG. 4B).

Show it:

FIG. 1

a first embodiment of a Naßbohrkrone with a spiral tubular Bohrschaft, which was prepared by the method according to the invention for producing a drill shank with recesses on the inside;

FIGS. 2A, B

a longitudinal section through the drill shank of the first wet bit of FIG. 1 along the section line AA in FIG. 1B ( FIG. 2A ) as well as a detail of the drill shank of the FIG. 2A in an enlarged view ( FIG. 2 B );

FIG. 3

a second embodiment of a Naßbohrkrone with a longitudinally welded drill stem, which was prepared by the method according to the invention for producing a Bohrschaftes with recesses on the outside and inside;

FIGS. 4A, B

a cross section through the drill shank of the second wet drill bit of FIG. 3 along the section line AA in FIG. 3 ( FIG. 4A ) as well as a detail of the drill shank of the FIG. 4A in an enlarged view ( FIG. 4B ).

FIG. 1 shows a first embodiment of a Naßbohrkrone 10 with a spiral-shaped drill shank, which was prepared by the inventive method for producing a drill shank with multiple recesses on the inside. The wet bit 10 is hereinafter referred to as the first wet bit 10 and comprises a cutting portion 11 , a Bohrschaftabschnitt 12 and a receiving portion 13 , wherein the cutting portion 11 and the Bohrschaftabschnitt 12 are connected via a first connecting means 14 and the Bohrschaftabschnitt 12 and the receiving portion 13 via a second connection means 15 are connected.

The first connection device 14 is formed in the embodiment as a releasable connection means in the form of a combined plug-and-turn connection and the second connection means 15 is formed in the embodiment as non-detachable connection means in the form of a welded connection. Alternatively, all releasable and non-releasable connection means for the first connection means 14 between the cutting portion 11 and the Bohrschaftabschnitt 12 and for the second connection means 15 between the Bohrschaftabschnitt 12 and the receiving portion 13. The first drill bit 10 may be a detachable first and second connection means fourteenth 15, a releasable first connecting device 14 and non-releasable second connecting device 15, a non-releasable first connecting device 14 and releasable second connecting device 15 or a non-releasable first and second connecting device 14, 15. A connection device is said to be detachable if the connection can be released non-destructively by the user, such as a plug connection, for example Pin connection or a threaded connection. A connection device is said to be non-detachable if the user can release the connection only by destroying the connection means, such as a solder connection, a welded connection or an adhesive connection.

The cutting portion 11 comprises a ring portion 16 and a plurality of cutting segments 17 which are connected to the ring portion 16. The cutting segments 17 are arranged in a ring shape and form a cutting ring with gaps. The cutting section 11 may instead of a plurality of cutting segments 17 also have a single formed as a closed cutting ring cutting segment. The cutting segments 17 are welded to the ring portion 16, soldered, screwed or fastened in another suitable manner of attachment to the ring portion 16. In the case of a non-releasable first connecting device 14, the annular section 16 can be dispensed with and the cutting segments 17 can be connected directly to the drill shaft section 12.

The drill shaft section 12 comprises a spiral-shaped drill shaft 18 , which is connected to the cutting section 11 via the first connection device 14 and to the receiving section 13 via the second connection device 15. The receiving portion 13 comprises a lid 21 and a spigot end 22 , via which the first wet bit 10 is fastened in a tool holder of a core drilling apparatus. In the drilling operation, the first wet bit 10 is driven by the core drill around a drilling axis 23 and moved in a drilling direction 24 parallel to the drilling axis 23 in a workpiece to be machined 25 . The first wet bit 10 produces in the workpiece 25 a core 26 having a core diameter d ₁ and a bore 27 having a diameter d ₂ . The cutting segments 17 form a cutting ring having an inner diameter corresponding to the core diameter d ₁ and an outer diameter corresponding to the borehole diameter d ₂ .

FIGS. 2A B shows a longitudinal section through the drill shank 18 of the first wet bit 10 of FIG FIG. 1 along the section line AA in FIG. 1B ( FIG. 2A ) and a detail of the drill shank 18 of the FIG. 2A in an enlarged view ( FIG. 2 B ).

The drill shank 18 is formed as a welded spiral tube body made of a strip material 31 in the form of a flat sheet by forming and welding. The flat strip material 31 was converted into a spiral tube body 32 and connected at the strip edges via a spiral connection weld 33 . The spiral connection weld 33 acts as a stiffening element for the drill shank 18 and increases the rigidity of the drill shank 18 with respect to a tubular drill shank of the same wall thickness.

The spiral connection weld 33 protrudes beyond the spiral tube body 32 on an outer side 34 of the drill stem 18 with an outer projection Δ _A and is formed on an inner side 35 of the drill stem 18 substantially flush with the spiral tube body 32. In order to produce the spiral connection weld 33 projecting on the outer side 34, a suture material 36 is used during welding of the spiral tube body 32, which provides the required material volume.

The suture 36 may be powdered, wire-shaped or band-shaped. By way of the material properties of the suture material 36, the properties of the spiral connection weld 33 can be adapted. The suture 36 may have the same material properties or different material properties as the band material 31. When suture 36 and band material 31 have the same material properties, a uniform transition is created when the band edges are welded, and suture 36 can bond well with band material 31. Through the use of suture material 36, which has a higher tensile strength and / or wear resistance than the strip material 31, the properties of the spiral connection weld 33 can be influenced so that the guidance of the drill shaft 18 via the spiral connection weld 33 is possible during the entire service life of the drill shaft 18 is guaranteed.

The first wet bit 10 shows a spiral connection weld 33, which projects beyond the outer side 34 of the drill stem 18. The protruding on the outer side 34 helical joint weld 33 allows drilling the first Naßbohrkrone 10 a guide of the drill shaft 18 via the hole 27. Alternatively, the spiral connection weld 33 on the outer and inner side 34, 35 of the drill shank 18 with an outer and Inner projection Δ _A , Δ _I or on the inner side 35 of the drill shank 18 with an inner projection Δ _I with respect to the spiral tube body 32 survive. The projection of the spiral connection weld 33 is adjusted so that the spiral connection weld 33 on the outer side 34 of the drill shaft 18 with the wellbore 27 or on the inside 35 of the drill shaft 18 with the core 26 in contact. Due to the protruding spiral connection weld 33, the drill shank 18 has a small contact surface to the borehole 27 or to the core 26 and generates a low friction. The lower the friction on the outer side 34 between the drill shank 18 and the borehole 27 or on the inner side 35 between the drill shank 18 and the core 26, the greater is the rate of advance of the first wet bit 10 for the same performance of the core drill and the life of the drill shank 18 is increased.

When wet drilling with the first wet core bit 10, a cooling and rinsing liquid is required, which cools the cutting segments 17 as cooling liquid and removes cuttings from the borehole 27 as rinsing liquid. The protruding on the outer side 34 of the drill shank 18 helical joint weld 33 can assist in addition to the leadership of the drill shank 18 through the wellbore 27 the removal of offset with cuttings, spent cooling and rinsing liquid. The spiral connection weld 33 acts as a conveyor coil for the cutted, spent cooling and rinsing liquid when the direction of rotation of the first wet bit 10 and the direction of the spiral connection weld 33 on the outside 34 of the drill shank 18 match.

In order to supply clean cooling and rinsing liquid on the inside 35 of the drill shank 18, on the inner side 35 of the drill shank 18, three recesses 37A, 37B, 37C are arranged, which are referred to as first recess 37A, second recess 37B and third recess 37C. The recesses 37A, 37B, 37C are generated before the forming of the strip material 31 to the spiral tube 32 in the sheet and are used in wet drilling with the first wet core bit 10 as a transport channel for the necessary cooling and rinsing liquid. The recesses 37A, 37B, 37C are necessary above all with a small inner gap between the core 26 and the drill stem 18. The number of recesses 37A, 37B, 37C, the geometry of the recesses 37A, 37B, 37C and the arrangement of the recesses 37A, 37B, 37C on the outside 34 and / or inside 35 of the drill shank 18 can be related to the amount of liquid of the cooling and rinsing liquid be adjusted.

The recesses 37A, 37B, 37C provided on the inner side 35 of the drill shank 18 serve to supply clean cooling and rinsing liquid, and recesses provided on the outer side 34 of the drill shank 18 can support the removal of spent, cooled and flushed liquid mixed with drill cuttings. Since the recesses 37A, 37B, 37C are produced in the first wet bit 10 prior to forming the strip material 31, indentations can be made on the inside 35 of the drill stem 18 with little manufacturing effort.

FIG. 3 shows a second embodiment of a Naßbohrkrone 40 with a longitudinally welded drill stem, which was produced by the method according to the invention for producing a drill shank. The wet bit 40 is hereinafter referred to as a second wet bit 40 and comprises a cutting portion 41 , a Bohrschaftabschnitt 42 and a receiving portion 43 , wherein the cutting portion 41 and the Bohrschaftabschnitt 42 are connected via a first connecting means 44 and the Bohrschaftabschnitt 42 and the receiving portion 43 via a second connection means 45 are connected.

The cutting section 41 comprises a plurality of cutting segments 47 which form a cutting ring having an inner diameter corresponding to the core diameter d ₁ and an outer diameter corresponding to the borehole diameter d ₂ . The drill shaft section 42 comprises a longitudinally welded drill shaft 48 , which is connected to the cutting segments 47 via the first connecting device 44 and to the receiving section 13 via the second connecting device 45. The receiving section 43 comprises a cover 51 and a spigot 52 , via which the second wet drill bit 40 in FIG a tool holder of a core drill is attached.

The first and second connection means 44, 45 are formed in the embodiment as non-detachable connection means in the form of a welded connection. In principle, each first connecting device 44, which connects the cutting section 41 and the drill shaft section 42 releasably or non-detachably, and each second connecting device 45, which connects the drill shaft section 42 and the receiving section 43 releasably or non-detachably.

The drill shank 48 is in the form of a longitudinally welded longitudinal tube body and was made of three strip materials 53A, 53B, 53C in the form of flat sheets by forming and welding. The strip materials 53A, 53B, 53C were formed into a longitudinal tube body 54 in a molding installation and bonded in a welding system at the strip edges via three longitudinal connecting welds 55A, 55B, 55C . The band materials 53A, 53B, 53C are referred to as first band material 55A, second band material 55B and third band material 55C, and the joint welds are referred to as first joint weld 55A, second joint weld 55B and third joint weld 55C. The first joint weld 55A connects the first and second band materials 53A, 53B, the second joint weld 55B connects the second and third band materials 53B, 53C, and the third joint weld 55C connects the first and third band materials 53A, 53C.

The second wet drill bit 40 has a cutting section 41 with a plurality of cutting segments 47, which are permanently attached to the drill shaft 48 by means of the first connecting device 44. The cutting section 41 may instead of a plurality of cutting segments 47 also have a single designed as a closed cutting ring cutting segment. In addition, the cutting portion 41 may include a ring portion disposed between the cutting segments 47 and the drill shaft 48. The cutting segments 47 are welded, soldered, screwed or fastened in another suitable manner of attachment to the ring section on the ring section and the ring section and the drill shank 48 are detachably or non-detachably connected by means of the first connection device 44. The ring portion may be formed as the drill shaft 48 as longitudinally welded pipe. However, in the case of thin strip materials 53, the use of tubular ring sections with a constant wall thickness is advisable, since a larger contact surface is available for fastening the cutting segments 47.

FIGS. 4A B show a cross-section through the drill shank 48 of the second wet bit 40 of FIG FIG. 3 along the section line AA in FIG. 3 ( FIG. 4A ) and a detail of the drill shank 48 of FIG. 4A in an enlarged view ( FIG. 4B ).

The longitudinal connecting welds 55A, 55B, 55C of the drill shank 48 are formed on an outer side 56 of the drill shank 46 is substantially flush with the longitudinal tube body 54 and are on an inner side 57 of the drill shank 48 with an inner projection Δ _I with respect to the longitudinal tube body 54 via. The longitudinal joint welds 55A, 55B, 55C protruding on the inner side 57 of the drill shank 48, when bored with the second wet bit 40, allow the drill shank 48 to be guided over the core 26. To create the projecting longitudinal joint welds 55A, 55B, 55C, welding is performed of the longitudinal tube body 54 uses a suture 58 which provides the required volume of material.

The suture 58 may be powder, wire or ribbon. By the material properties of the suture 58, the properties of the joint welds 55A, 55B, 55C can be adjusted. The suture 58 may have the same material properties or different material properties as the band materials 53A, 53B, 53C. When the suture 58 and the band materials 53A, 53B, 53C have the same material properties, a uniform transition occurs when the band edges are welded, and the suture 58 can bond well with the band materials 53A, 53B, 53C. By using suture material 58 having, for example, a higher tensile strength and / or a higher wear resistance than the band materials 53A, 53B, 53C, the properties of the joint welds 55A, 55B, 55C can be influenced.

The second wet bit 40 shows a drill shank 48 with connecting welds 55A, 55B, 55C, which protrude at the outer and inner side 56, 57 of the drill shank 48 with respect to the longitudinal tube body 54. Alternatively, the joint welds 55A, 55B, 55C on the outside 56 of the drill stem 48 with the outer supernatant Δ _A or on the inside 57 of the drill shank 48 with the inner supernatant Δ _I with respect to the longitudinal tube body 54 survive. The overhang of the joint welds 55A, 55B, 55C is adjusted so that the joint welds 55A, 55B, 55C contact the core 26 after drilling on the outside 56 of the drill shank 48 with the bore 27 or on the inside 56 of the drill shank 48 ,

When wet drilling with the second wet core bit 40, a cooling and rinsing liquid is required, which cools the cutting segments 47 as coolant and removes cuttings from the borehole 27 as flushing liquid. In order to supply clean cooling and rinsing liquid to the inner side 57 of the drill shank 48, a plurality of indentations 59 are arranged on the inner side 57 of the drill shank 48. The depressions 59 are generated before forming the band materials 53A, 53B, 53C to the longitudinal tube body 54 in the plate and are used in wet drilling with the second wet core bit 40 as a transport channel for the necessary cooling and rinsing liquid. The depressions 59 are necessary, above all, with a small inner gap between the core 26 and the drill shank 48. The number of recesses 59, the geometry of the recesses 59 and the arrangement of the recesses 59 on the outside 56 and / or inside 57 of the drill shank 48 can be adapted to the liquid quantity of the cooling and rinsing liquid.

Claims (6)

A method of making a drill bit (18; 48) for a wet bit (10; 40) that produces a wellbore (27) having a well diameter (d ₂ ) and a core diameter (d ₁ ) core (26), comprising: ▪ N, N ≥ 1 strip materials (31; 53A, 53B, 53C) are formed into a tube body (32; 54) and ▪ the tube body (32; 54) is bonded to the band edges by N connecting welds (33; 55A, 55B, 55C), characterized in that at least one strip material of the N, N ≥ 1 strip materials (31; 53A, 53B, 53C) is provided with at least one recess (37A, 37B, 37C; 59) prior to the material-locking connection of the strip edges. A method according to claim 1, characterized in that the N, N ≥ 1 strip materials (31) are formed into a spiral tube body (32) and the spiral tube body (32) at the band edges via N spiral connection welds (33) is materially connected. Method according to claim 1, characterized in that the N, N ≥ 1 strip materials (53A, 53B, 53C) are formed into a longitudinal tube body (54) and the longitudinal tube body (54) is formed at the strip edges by N longitudinal connecting welds (55A, 55B, 55C ) is materially connected. Method according to one of claims 1 to 3, characterized in that the at least one recess (37A, 37B, 37C; 59) of the tubular body (32; 54) is produced on an inner side (35; 57) of the drill shank (18; 48) , Method according to one of claims 1 to 3, characterized in that the at least one recess of the tubular body (32; 54) on an outer side (34; 56) of the drill shank (18; 48) is generated. Method according to one of claims 1 to 3, characterized in that at least one recess (37A, 37B, 37C; 59) of the tubular body (32; 54) on an inner side (35; 57) of the drill shank (18; 48) and at least one Deepening of the tubular body (32; 54) on an outer side (34; 56) of the drill shank (18; 48) are generated.

Images